<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>login validate</title>
    <style type="text/css">
        html,body,div{
            margin: 0;
            padding: 0;
            height: 100%;
        }
        div{
            background-color: #FFF8DC;
        }
    </style>
</head>
<body>
<div>
    酱紫div高度就和屏幕高度一样啦~~
</div>
</body>
</html>